In marine vessels, a dominant approach for generating thrust to move the vessel across the water involves usage of marine propulsion. At a very high level, a marine propulsion system includes a propeller attached to a rotatable shaft, whereas one or more engines in the vessel are arranged to rotate the shaft, thereby providing the thrust needed for moving the vessel. Characteristics of these (and other) components of a marine propulsion system are designed such that a desired or required amount of thrust and desired operational efficiency is provided e.g. in view of the hull design of the vessel and size of the vessel. In some scenarios, in order to reach desired/required amount of thrust and/or operational efficiency, a vessel may be provided with a plurality of marine propulsion systems like the one outlined above.
In use, some parts of the marine vessel are immersed in water for prolonged periods of time, which gradually lead to fouling of some underwater components of the vessel. Especially fouling of lower parts of the hull of the marine vessel and the propeller e.g. due to marine growth may result in a significant degradation of the vessel performance. As a consequence of the fouling, the thrust generated by the propulsion system at a certain engine output power may be significantly reduced and/or the engine(s) may need to be driven to provide a higher-than-designed output power in order to generate the desired/required amount of thrust. These factors contribute to increased fuel consumption, to prolonged journey time to a destination or both, potentially leading to undesired economic effects in one way or another.
While periodic cleaning of the underwater parts of a marine vessel is a straightforward solution for addressing such causes of degraded marine vessel performance, a cleaning procedure is typically both time-consuming and involves an additional cost, and therefore it is highly desirable to ensure that the cleaning of the underwater parts of the marine vessel is undertaken only when strictly required. In this regard, various techniques for estimating the effect of a performance loss due to fouling of the underwater parts of a marine vessel have been proposed. However, there is a continuous need for improved and more accurate performance estimation techniques to ensure that cleaning and maintenance of the underwater parts of the vessel are undertaken only when improvement in vessel performance after the cleaning/maintenance can be assumed to outweigh the downtime and cost incurred due to the cleaning and maintenance operations.